“…Among these studies, 9 studies carried out in America [10,11,17,18,20,21,22,26,28], 9 studies in Europe [2,16,19,23,24,25,27,31,33]and3 studies in Asia [29,30,32]. Eight studies were published before 2005 [10,11,19,22,25,31,32,33]and 13 afterwards [2,16,17,18,20,21,23,24,26,27,28,29,30].…”